The present invention relates generally to a post driver machine and, more particularly, to a weight catch mechanism which is especially adapted to prevent the post driver machine from “dry-firing” when there is no post engaged with the post driver machine.
A post driver machine is used for driving large posts into the ground. In general, post drivers utilize a pile driving principle in which a weight is raised to some distance above a post, and is then dropped in order to drive the post into the ground. Such post drivers rely on a post being present to dissipate the energy of the falling weight. When a post is properly positioned within the post driver, the kinetic energy of the falling weight is transferred into the post, pushing it into the ground. However, when a post is not properly positioned within the post driver, the weight may fail to contact the post upon falling, and may instead impact upon the frame of the post driver. Such a so-called “dry-fire” can damage the post driver apparatus. Repeated dry-firing often results in damage to the framework and mechanical structure of the post driver machine. Additionally, each dry-fire is time lost, as the post driver machine must be repositioned and the weight lifted back up and dropped again.
Thus, the presence or absence of a post within a post driver machine has important consequences for the post driver machine's performance and structural integrity. In many existing post driver machines, once the process of lifting and dropping the weight (called a “cycle” or a “stroke”) has been initiated, the stroke will occur regardless of whether a post is positioned within the machine. Generally, it is left to the operator of the apparatus to decide when a stroke should occur. However, operator error is often of great concern.
A post driver machine is typically attached to a front loader, skid-steer, backhoe or similar vehicle so that the machine can be moved from location to location, allowing posts to be easily placed into the ground at desired locations. The operator's view of the post in the post driver is often at least partially obscured by the body of the post driver itself. Therefore, the operator may not be in the best position to decide when the post is properly positioned to initiate a stroke.
Thus, in current designs for post driver machines, there is therefore a need for preventing dry-firing, and largely removing the possibility for operator error.